how can i set time value to 00:00:00 in the dateformat such as Tue Dec 28 17:36:28 IST 2010?

I'm using Java and I'm trying the below piece of code

Calendar cal1 = Calendar.getInstance();  
cal.setTime(now1);
cal1.add(Calendar.DAY_OF_YEAR, -1);  
java.util.Date yesterday =开发者_开发知识库 (Date) cal1.getTime();  
System.out.println(yesterday.toString());
java.sql.Timestamp yesterdayTimestamp = new java.sql.Timestamp(tomorrow.getTime());
System.out.println(yesterdayTimestamp.toString()); 

which gives me the output as Tue Dec 28 17:36:28 IST 2010 Now I want to set the time in this to 00:00:00 then Tue Dec 28 17:36:28 IST 2010 will be Tue Dec 28 00:00:00 IST 2010

I'm not getting how to do this?

If I have understand problem correctly you want to set time related fields to be set to 0.

        Calendar cal1 = Calendar.getInstance();  
        cal1.set(Calendar.HOUR_OF_DAY, 0);
        cal1.set(Calendar.MINUTE, 0);
        cal1.set(Calendar.SECOND, 0);
        cal1.set(Calendar.MILLISECOND, 0);
        System.out.println(cal1.getTime());

Output

Wed Dec 29 00:00:00 IST 2010

You need to set the individual elements of the time component.

http://download.oracle.com/javase/1.5.0/docs/api/java/util/Calendar.html#set(int, int)

cal1.set(Calendar.HOUR_OF_DAY, 0);
cal1.set(Calendar.MINUTE, 0);
cal1.set(Calendar.SECOND, 0);

if you just need date , not time , you should use java.sql.Date.

In your calendar you can set the respective fields to 0: cal.set(Calendar.HOUR_OF_DAY, 0).

Alternatively, you can use joda-time, which has the DateMidnight class for that purpose.

Btw, as noted in the comments - use a formatter. SimpleDateFormat for example. You should not rely on the toString() representation of an object.